2/23/2006

Why flowers come in colors

While many of us are dreaming of the fantastic flowers that await us this spring, have you ever wondered why there are so many beautiful colors to choose from?

Part of the reason is that different animals are attracted to different colors. A colorful flower is just an advertisement to a humming bird or butterfly. "Come here, I have nectar" scream the flowers wordlessly through their bright colors.

But not all animals are attracted to the same colors. Have you noticed how the bumble bees tend to flock toward blue and violet flowers, like clover or vitex? Meanwhile, I've watched hummingbirds feed on orange-red daylilies snubbed by the bees. Pollinators are particular about their favorite colors, leading to lots of color variation in wild flowers. This is fortunate, since it gives us more colors for us to choose from in our gardens.

So what colors do critters prefer, and what's the attraction? It's more than just having a favorite color; there's good reasons for their selections.

Moths and Bats tend to feed on white flowers. These animals both feed at night, and the white colored flowers reflect the most light, and therefore are most visible to night-time feeders. Some of these bat-fertilized flowers bloom only at night. I found a picture of a typical bat-pollinated flower posted on the UCLA botanical gardens' web site.As many of you gardeners know, butterflies have a keen sense of color. They flock to bright colors from yellow to blue to red. Common plants grown in butterfly gardens, such as the milk weedfavored by monarch butterflies, come in bright pinks, oranges, and purples. Butterflies especially like the butterfly bush. I love to post pictures of the tiger swallow-tail and gulf fritlillary I've seen in my garden. These butterflies love the tiny clusters of flowers on the butterfly bush since there's ample room to land and feed. Jill at Once Daily posted a lovely close-up of a feeding butterfly.

Humming birds don't need a place to land, and often feed from long slender flowers. For example, their long beaks can easy feed from the trumpet vine as they hover. Hummingbirds like red and orange flowers, hence feeders are usually made in this color.

Red is the least favorite color of bees, however. I love Jill's pictures of bees, like this Carpenter bee on a clover flower. Notice they tend to favor purples and blues. Unlike us, bees can also see UV light, and some flowers have UV lines that are invisible to us, but these UV markings are valuable guides to bees. On the otherhand, bees cannot see red. Just like UV light and infrared light is out of our human range of vision, the red spectrum of light is not visible to bees. So insects actually see color differently, as shown by this image projecting a bug's view of a plant on the Bog Blog.

So if you're planning a colorful garden, thank those variety of pollinators out there, from bees to birds, for their discriminating tastes in color!